The present invention relates to a valve tappet system, in particular a bucket tappet having a cam follower surface with a convex curvature such as that which may be provided, for example, in an internal combustion engine for actuating the gas exchange valves. This invention also relates to an anti-rotation device for a valve tappet system for preventing a base body of the valve tappet system from rotating or swiveling about its axis of oscillation.
DE 43 42 199 A1 describes an anti-rotation device for a valve tappet. This valve tappet is designed as a bucket tappet and is provided with a passage at the side, i.e., in the area of the lateral surface of the tappet. A guide element formed by a spiral compression spring is inserted into this passage. The spiral compression spring is accommodated in the passage in such a way that a lateral area of the spiral compression spring protrudes radially above an outer lateral surface of the bucket tappet. In the installed position, this radially protruding section of the spiral compression spring is inserted into a guide groove provided on the cylinder head; as a linear guide element, it prevents a swiveling motion of the bucket tappet about its axis of oscillation.
DE 43 02 877 C2 describes a similar tappet in which the guide element mentioned above is designed as a cylindrical pin and is inserted laterally into a lateral surface of the tappet in the same way as the spiral compression spring.
DE 196 00 852 A1 describes an anti-rotation tappet on which the lateral area is provided with a passage into which a guide element is inserted so that a guide section of same protrudes radially beyond the lateral area. This protruding area is inserted in the installed position into a guide groove near the cylinder head, thereby preventing in a known way a rotational or swiveling motion of the tappet about its axis of oscillation.
DE 101 10 914 A1 and U.S. Pat. No. 3,822,683 disclose additional anti-rotation devices for valve tappets in which a guide element provided for preventing rotation in the circumferential direction is inserted into a passage in a lateral area of the valve tappet.
Anti-rotation device for valve tappets are necessary in particular when the cam follower surface, which comes in contact with the respective cam at least temporarily—and is actuated by the cam—is designed with a curvature, e.g., with a camber.